まつろわぬ者たちの掟2

It is important to know that Tetsuya possesses in this quest a skill ( likely Gambler ) that grants him Critical++ when attacking, be mindful that it can easily wipe your units in range if you get unlucky especially during phase 2. If able attempt to keep him away from the midle cell so you can easily abuse AI behavior or patch up your units before moving back up.